With regard to the application of a Scanning Electron Microscope (SEM) and a Focused Ion Beam (FIB) apparatus, etc. to semiconductor devices, it becomes more important to observe and process the three-dimensional structure or shape by observing a specimen from many directions. For example, when a SEM is used to observe a two-dimensional specimen such as a wafer conventionally from the direction vertical to the specimen surface while a need arises today to observe the cross-section structure of a device vertical to the specimen surface. In addition, when an FIB apparatus is used to separate a very small specimen from a specimen substrate or to fabricate a thin-film specimen of even film thickness, a tilted specimen is observed or processed.
JP-A-04-132909 (Patent Literature 1) discloses a technology in which the deflection pattern of an electron beam has a trapezoidal shape and a rectangular scan area is formed on a tilted specimen.